1. Field of the Invention
This invention relates to furnaces in general and is more particularly directed to an improved furnace structure and a method of making the same. Specifically, the furnace structure involved uses a shell of integral poured concrete and provides for the introduction of tertiary air at positions spaced around and along the length of the combustion zone.
2. Brief Description of the Prior Art and Development of the Invention
There have been problems in the past with regard to inefficiency in furnace combustion chambers in that combustion of fuel is incomplete. This has been particularly true in combustion chambers for furnaces of the type used in connection with steam boilers and the like. Such boilers and other heating systems are normally fed a mixture of fuel and primary combustion air through a nozzle extending into the combustion chamber. Secondary air enters around the nozzle.
In my U.S. Pat. No. 3,174,530, issued Mar. 23, 1965, I described such a combustion chamber associated with a steam boiler. In that construction, the combustion chamber is substantially enclosed in refractory brick. The boiler shell includes a number of horizontal return water tubes, each of which is in fluid communication at its forward end with a header into which is introduced. The burner is mounted in an end wall for introducing the mixture of fuel and air which is ignited to produce a flame extending generally over the length of the combustion chamber. Tertiary air can be introduced through the combustion chamber walls through copper supply tubes or the like, but it has been found that when such tubes are exposed to the immense heat of the combustion chamber, they tend to deteriorate and require replacement for proper continued operation of the furnace. Replacement of the tubes can, in some cases, require a complete rebuilding of the combustion chamber wall.
Another problem that has existed with furnaces generally is the deterioration of the combustion chamber wall over extended periods of use to the extent that the wall has to be relined regardless of the presence or absence of air delivery tubes. Such relining operations generally require rebuilding of the wall from refractory brick and are costly.